Interaction of the drilling fluid with shale is a major cause of wellbore instability. The clay minerals present in the shale, such as kaolinite, bentonite, smectite, and montrolite interact with the water present in the drilling fluids, and this interaction can cause wellbore instability. For example, the clay minerals swell when they interact with the water, then expand and slough off. This shale sloughing reduces efficiency of the drilling fluid to lift the drilled cuttings and decreases the structural integrity of the wellbore. In some instances, the shale can weaken, and eventually collapse into the wellbore. Shale inhibition fluids are utilized to minimize this interaction.